Hey Akash

Computerized Numerical Control (CNC) is mainly used for controlling digital machines especially Computers through programmed protocols and systems.

Computer Aided Design (CAD) is used for designing and optimization of various structures and models. They have nice scope in the future, to learn CAD-CNC you can follow:

• MOOC platforms like Coursera, Udemy
• Standard book;
  CNC Programming Techniques by Peter Smid
  AutoCAD for Dummies by Bill Fane

For further doubts, ask us.